Using a Graphing Calculator To Determine a First-Order Rate Constant: Author ReplyJosé E. Cortés-FigueroaWhen technology is used to help with mathematical calculations, the emphasis must be on the concepts being learned rather than simply the procedures. In our approach we are attempting to help students learn more about the concept and also to attain data analysis skills they will need in the future. Cortés-Figueroa, José E. J. Chem. Educ.2004, 81, 485.

There Seems To Be Uncertainty about the Use of Significant Figures in Reporting Uncertainties of ResultsJulio F. Caballero and Delphia F. HarrisA cursory review of two journals indicates that uncertainties in experimental results are not consistently reported in the literature with the correct number of significant figures. The problem seems more frequent in computer generated results in both chemical education and research articles. Examples of published values with uncertainty inappropriately reported are included along with the appropriate rounding. Caballero, Julio F.; Harris, Delphia F. J. Chem. Educ.1998, 75, 996.

Laboratory Equipment / Apparatus |

Learning Theories |

Chemometrics

Precision and Accuracy in Measurements: A Tale of Four Graduated CylindersRichard S. TreptowThe concepts of precision and accuracy help students understand that uncertainty accompanies even our best scientific measurements. A model experiment can be used to distinguish the two terms. The experiment uses four graduated cylinders which give measurements of different accuracy and precision. Such terms as mean, range, standard deviation, error, and true value are defined through an illustration.Treptow, Richard S. J. Chem. Educ.1998, 75, 992.

Rounding Numbers: Why the "New System" Doesn't WorkW. Robert MiddenThis paper explains a correction to the rounding rule previously published in this Journal. The earlier article reported that the best way to round numbers is to always round up when the first digit dropped is 5. However, this will lead to accumulation of error when errors are averaged.Midden, W. Robert. J. Chem. Educ.1997, 74, 405.

Solving equilibria problems with a graphing calculator: A robust method, free of algebra and calculus Ruch, David K.; Chasteen, T. G.The method of successive approximations is frequently introduced in freshman chemistry as a means for solving equilibrium equations. However, this often requires an understanding of calculus that is problematic for introductory chemistry students. An alternative method to solving such equations is to use graphic calculators to solve problems graphically.Ruch, David K.; Chasteen, T. G. J. Chem. Educ.1993, 70, A184.

More on the Question of Significant FiguresClase, Howard J.Because so many students have a hard time understanding what significant figures are all about, this author developed a method using "?" to substitute for insignificant zeros. This helps many students finally grasp this convention.Clase, Howard J. J. Chem. Educ.1993, 70, 133.

Chemical equilibrium: III. A few math tricks Gordus, Adon A.The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.Gordus, Adon A. J. Chem. Educ.1991, 68, 291.

Acids / Bases |

Equilibrium |

Chemometrics |

Titration / Volumetric Analysis

Accuracy of measurements and the U.S. CensusGorin, GeorgeSome aspects of taking the Census can help students to understand the problem of measurement error and the use of significant figures.Gorin, George J. Chem. Educ.1990, 67, 936.

The length of a pestle: A class exercise in measurement and statistical analysisO'Reilly, James E.Too many students get through chemistry without acquiring a basic understanding and appreciation of the concepts of measurement science. The purpose of this report is to outline an extremely simple class exercise as a concrete paradigm of the entire process of making chemical measurements and treating data.O'Reilly, James E. J. Chem. Educ.1986, 63, 894.

Empirical formulas - A ratio problemKnox, KerroA problem involving an analogy between ratios of boys to girls given their average weights and percentage composition of the class by weight.Knox, Kerro J. Chem. Educ.1980, 57, 879.